LevelDB and CouchDB
ØThe current options for the peer state database are LevelDB and CouchDB.
Ø
Ø LevelDB is the default key-value state database embedded in the peer process.
Ø
ØCouchDB is an alternative external state database. Like the LevelDB key-value store, CouchDB can
store any binary data that is modeled in chaincode (CouchDB attachments are used internally for
non-JSON data).
Ø
ØAs a document object store, CouchDB allows you to store data in JSON format, issue JSON queries
against your data, and use indexes to support your queries.
https://hyperledger-fabric.readthedocs.io/en/release-2.2/couchdb_as_state_database.html

To install
https://docs.couchdb.org/en/latest/install/unix.html#installation-using-the-apache-couchdb-convenie
nce-binary-packages
to verify
https://pouchdb.com/guides/setup-couchdb.html
Browser
http://localhost:5984/_utils/
CouchDB

ØCaliper is a blockchain benchmark framework which allows users to measure the performance of a
specific blockchain implementation with a set of predefined use cases.
Ø
ØCaliper will produce reports containing a number of performance indicators, such as TPS
(Transactions Per Second), transaction latency, resource utilisation etc.
Ø
ØThe intent is for Caliper results to be used as a reference in supporting the choice of a
blockchain implementation suitable for the user-specific use-cases.
Ø
ØGiven the variety of blockchain configurations, network setup, as well as the specific use-cases
in mind, it is not intended to be an authoritative performance assessment, nor to be used for
simple comparative purposes (e.g. blockchain A does 5 TPS and blockchain B does 10 TPS, therefore B
is better).
Ø
ØThe Caliper project references the definitions, metrics, and terminology as defined by the
Performance & Scalability Working Group (PSWG).
Hyperledger Caliper

Key Characteristics
•A unified blockchain benchmark framework. We provide a common layer to integrate with major
existing blockchain framework/platforms, so that the same benchmarks can be run for different
blockchain systems Some benchmark test environment will be provided to help different people run
tests under the same environment, blockchain management tools like Hyperledger Cello could be
integrated later to deploy and operate the environment. Also, users can use their existing
environment and configure Caliper to run the test under the environment.
•A commonly accepted definition of performance indicators. You cannot compare an apple and a pear
directly unless some common criteria are set. We will work closely with PSWG to provide a common
definition of performance indicators that users care about, such as TPS, latency, resource
utilization, etc.
•A set of commonly accepted benchmark cases. The goal of Caliper includes providing a set of easy-
understandable benchmark cases so that each blockchain solution can be compared in various
scenarios. This calls for much collaboration from PSWG, Requirement WG and other WG in Hyperledger
community as well as blockchain practitioners to cover as many use cases that are of user’s
interest as possible
CouchDB

https://hyperledger.github.io/caliper/v0.4.2/installing-caliper/
Installing and Running Caliper


The current latest version of node and npm:
node version 10.9.0
npm version 6.4.0
But, the current Hyperledger Fabric (release version 1.2) Prerequisites says that there should be:
node version 8.9.x or greater (but not 9.x or 10.x)
npm version 5.6.0
https://blog.chapagain.com.np/hyperledger-fabric-error-failed-to-load-grpc-binary-module-because-it
-was-not-installed-for-the-current-system/
Node js  and npm

Solution
To solve this error, we need to downgrade or set the node and npm version to the one specified in
the Prerequisites.
Set NPM version to 5.6.0
npm install npm@5.6.0 -g
Check NPM version
npm -v
Set Nodejs version to 8.9.4
– The Prerequisites says that the node version should be 8.9.x or greater.
– But, it should be in the range of 8.9.x.
– Node version 9.x or 10.x will give the same error.
– Therefore, we set the node version to 8.9.4. This version has worked well in my case.
Install NVM (Node Version Manager)
To set a specific node version, at first, we will install NVM (Node Version Manager).
You can run the nvm install script using either cURL or Wget.
using cURL:
curl -o- https://raw.githubusercontent.com/creationix/nvm/v0.33.11/install.sh | bash
Node js  and npm

Now, open a new window or new tab in the terminal.
List out the commands available for nvm:
nvm --help
Install and use specific node version using nvm
In our case, we will install and use node version 8.9.4.
nvm install v8.9.4 nvm use 8.9.4
After that, check the node version:
Check node version
node -v
Node js  and npm

One of the significant differences between Hyperledger fabric vs Composer is that Fabric is a
framework, and Hyperledger Composer is a tool. So, with Hyperledger Composer, you can create a new
platform of framework similar to Hyperledger Fabric. But with Fabric, you can't do that.
Hyperledger fabric vs Composer

Hyperledger Fabric cheat sheet
https://softwaremill.com/hyperledger-fabric-cheat-sheet/